How to Mask a High-Speed Land Rover? Paint it Like a Zebra

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Like 50,000-ton zebras, battleships from both world wars were
painted with high-contrast geometric patterns. The safari stripes
were an optical illusion meant to confuse the enemy as to a
ship's whereabouts and speed.

New research finds the patterns probably didn't help the
slow-moving ships hide their speed, but similar geometric
patterns could help distort the view of fast-moving objects, the
researchers say. Think Land Rovers covered in black-and-white
zigzags.

Camouflage is usually
used to conceal objects, by matching their color and patterns
to the background. This becomes an issue when the object is
moving through its environment, like a ship or tank. "Dazzle"
camouflage works in a different way, its aim to confuse and
bewilder the onlooker so they can't determine the size, speed and
heading of the object. [ Eye
Tricks: Gallery of Visual Illusions ]

"They didn't need to conceal the ship, they wanted to confuse the
enemy," said study researcher Nicholas Scott-Samuel of the
University of Bristol in the United Kingdom. "It's fairly
counterintuitive."

Dazzling difference

Dazzle camouflage is usually composed of high-contrast colors,
like black and white, arranged in geometric patterns.

This patterning on
World War I and II battleships was meant to throw off the aim
of enemy ships, whose rangefinders used images from two locations
to calculate the distance to an object; repetitive geometric
designs made it difficult to line up the two images correctly,
meaning the enemy's targeting would likely be off. As
range-finding improved, these tactics became less effective but
it was still assumed that the patterns might confuse other
perceptions of the ship, like how fast it was going.

To determine if this was true, Scott-Samuel and his colleagues
had participants indicate which of two shapes with different
patterns was moving faster. They did this for a series of image
pairs. They tended to judge the zigzag and checked patterns as
moving about 7 percent slower than the other patterns (such as
horizontal or vertical stripes), but only when the shapes were
moving at high speed (the equivalent of 8 miles per hour, or
13 kilometers per hour, from an observer 33 feet, or 10 meters,
away).

Three feet for survival

Extrapolating what they found in the lab, the researchers said
this would cause about a 3-foot (1 meter) aiming error of a
rocket-propelled grenade launched at a fast-moving object, like a
Land Rover driving 55 miles per hour (90 kph) from 230 feet (70
m) away, enough to save the lives of anyone riding in it.

" These
situations are less common these days, but possibly when you
have firefight, direct visual contact, that's when it would be
useful," Scott-Samuel said.

This effect could also be why zebras have high-contrast
striping, which hinder their predators' ability to track them
and make it harder to tell an individual apart from the herd.

The study was published June 1 in the journal PLoS ONE.

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